1. Field of the Invention
This invention relates to scraper and grader blades of the type which are termed utility blades, and which are adapted for connection behind, and operation from, three-point tractor hitch connections conventionally carried on tractors such as farm tractors.
2. Brief Description of the Present Invention
This invention is a utility blade which can be quickly and easily shifted or moved to a selected one of a plurality of operating positions, and which is carried at the rear of, and connected to, a tractor having a three-point hitch for connection of tilling tools and implements.
The utility blade of the invention includes an elongated beam having a forward end and a rear end. The forward end portion projects through a sleeve having a pair of lateral arms projecting therefrom, and secured to the sleeve for rotation with the sleeve about the axis of the boom. The rear end of the boom carries the utility blade which is mounted on the end of the boom so that it can be selectively rotated about a vertical axis extending through a pivot pin projected through the boom and through a turntable upon which the blade is carried.
The lateral arms which project from opposite sides of the sleeve which receives the forward end of the boom are swively or rotatably mounted in a pair of collars. These collars are adapted to be connected to the two lower, outside clevises or couplings of the three-point connection of a conventional agricultural tractor. The central and uppermost connection of the three-point connection carries a first or boom lifting hydraulic piston and cylinder subassembly which extends rearwardly and inclines downwardly. One end of the piston and cylinder subassembly is connected to a clevis plate carried on a fixed annular band secured to the rear end of the sleeve through which the boom extends. This first piston and cylinder subassembly is used to elevate and lower the boom about a horizontal pivotal axis which is coaxial with the axis of the two horizontally aligned lateral arms which project from opposite sides of the sleeve.
One side of the sleeve which receives one end portion of the boom defines a relatively large slot so that a pair of clevis plates can be secured to the lower side of the boom at this location and project through the slot in the sleeve. This facilitates the connection to such clevis plates of one end of each of a pair of second hydraulic piston and cylinder subassemblies which project outwardly and rearwardly at an angle to the boom and have their opposite ends connected to the utility blade. These second piston and cylinder subassemblies function to selectively rotate the blade about a large pivot bolt projected through the rear end of the boom, and through the blade turntable, so as to afford a high degree of selectivity in the positioning of the blade during its utilization.
The turntable by which the utility blade is mounted to the outer or rear end of the boom includes an upper plate which is secured to, and movable with, the rear end of the boom, and a lower plate which is secured to, and pivotable with, the blade. An annular retainer ring is positioned around the outer periphery of the lower side of the lower plate and is held axially in place by a plurality of ring clamping fingers or hooks which are secured to the top plate, project around the outer periphery of the lower plate, and are then turned under for securement to the annular retainer ring. A plurality of pin apertures are provided in the lower plate. These are positioned on a radius with respect to the pivot bolt upon which the blade is pivotally mounted such that these apertures are aligned radially with four pairs of align d pin apertures in the top plate and in the retainer ring. As the blade undergoes rotation about the pivot bolt extending through the boom and through the turntable formed by the upper and lower plates and retainer ring, a status of alignment of the successive pin holes is achieved so that the blade can be selectively positioned, and then retained in the selected position by insertion of retainer pins through the aligned pin holes in a manner hereinafter described.
An important object of the present invention is to provide an agricultural or construction utility blade assembly which can be secured behind, and operated from, a tractor having a standard three-point hitch at the rear end thereof. The utility blade of the assembly can be elevated with respect to the ground, can be adjusted by means of optionally usable gauge wheels with respect to the depth to which the blade will be allowed to cut into the earth, and can be rotated about a horizontal axis so as to, in effect, stand the blade on one end for purposes of trenching, ditch digging and the like.
Another object of the present invention is to provide a utility blade assembly which is very versatile in the blade attitude which it can be made to assume during earth working operations.
A further object of the invention is to provide a utility blade assembly which can be used for agricultural or construction purposes, and which is very ruggedly built, and is constructed to permit it to have an extended operating life with little need for maintenance or repairs during such operating life.
Additional objects and advantages will become apparent from the following detailed description when the same is read in conjunction with the accompanying drawings which illustrate a preferred embodiment of the invention.